1. Field of the Invention
The present invention relates to a light quantity detecting apparatus and an imaging apparatus. More particularly, the invention relates to a light quantity detecting apparatus for detecting a predetermined level of light by integrating the quantities of light received, and to an imaging apparatus utilizing that light quantity detecting apparatus for detecting quantities of light with an autofocus sensor arrangement.
2. Description of the Related Art
The autofocus (AF) sensor arrangement used to implement the automatic lens focusing function is generally made up of a plurality of CCD linear sensors (called AF sensors hereunder). Each of these AF sensors is equipped with the ability to end its light quantity integration on a predetermined output voltage under an integral control scheme. The integral control involves causing a plurality of AF sensors simultaneously to start integrating the quantities of received light and allowing each of the AF sensors to end its integrating process on a predetermined output voltage depending on illumination status. This type of technique is disclosed illustratively in Japanese Patent No. 3581031 and Japanese Published patent Laid-open No. 2001-305422.
Usually, the quantity of incident light varies from one AF sensor to another. That means different AF sensors have different integration end timings. For that reason, each AF sensor has the function of notifying its integration end timing and its integration end sequence information.
Under the above scheme of integral control using CCD linear sensors for autofocus purposes, a monitor sensor is furnished close to each AF sensor configured in order to detect the integrated light quantity of the corresponding AF sensor. For light quantity detection, it is assumed that the integration of the light incident on a given AF sensor is equivalent to the integration of the light incident on the monitor sensor located nearby.
The integral control scheme involving multiple AF sensors requires that the quantity of light be detected with precision by each monitor sensor. During the manufacture of AF-use CCD linear sensors, it is necessary to examine whether the feature of notifying the detected light quantity with each monitor sensor (i.e., automatic integration end timing) normally functions, illustratively with regard to a plurality of CCD linear sensors formed on a wafer before they are packaged.